Condensed Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Feb. 28, 2022	Feb. 28, 2021
Operating activities:
Net income	$ 724,388	$ 1,003,619
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation	980,525	938,493
Stock options issued for services	125,764	49,717
Paycheck Protection Program debt forgiveness	0	(1,461,500)
Changes in other assets and liabilities:
Accounts receivable	(1,147,600)	794,814
Inventory	38,591	1,193,304
Costs and estimated earnings in excess of billings	178,192	743,206
Other current assets	109,225	(420,881)
Accounts payable	(617,153)	(164,375)
Accrued commissions	84,181	96,235
Billings in excess of costs and estimated earnings	(653,856)	(644,042)
Other current liabilities	565,787	(103,650)
Net operating activities	388,044	2,024,940
Investing activities:
Acquisition of property and equipment	(721,969)	(1,089,069)
Other investing activities	(8,371)	(22,391)
Net investing activities	(730,340)	(1,111,460)
Financing activities:
Proceeds from issuance of common stock, net	12,335	11,411
Net change in cash and cash equivalents	(329,961)	924,891
Cash and cash equivalents - beginning	20,581,604	15,159,827
Cash and cash equivalents - ending	$ 20,251,643	$ 16,084,718